Cleaning towel



Jan. 27, 1970 L. M. PRlNCE 3,491

' CLEANING TOWEL Original Filed Oct. 15, 1964 ABRASIVE PARTICLES I2-----PAPER 10 VENTOR. LE M. PRINCE his ATTORNEYS United States PatentOffice 3,491,495 Patented Jan. 27, 1970 3,491,495 CLEANING TOWEL Leon M.Prince, Westfield, N.J., assignor to Lever Brothers Company, New York,N.Y., a corporation of Maine Continuation of application Ser. No.404,050, Oct. 15, 1964. This application Sept. 20, 1968, Ser. No.768,597 Int. Cl. B24d 11/00; 1524b 1/00 U.S. Cl. 51-394 9 ClaimsABSTRACT OF THE DISCLOSURE A cleaning towel comprising a highlyabsorbent substrate coated with a dry cleaning composition whichincludes a binder, a porous low bulk density cleaning powder and a highbulk density carrier powder in pro portions of from about one part toabout six parts by weight carrier powder to about one part by weightcleaning powder. Substantially all of the particles have particle sizesless than about 40 microns and at least 40% by weight have particlesizes greater than about 10 microns. The cleaning towels areparticularly well suited for cleaning glass surfaces and are preferablyused by first wetting the glass and then rubbing the wetted surface withthe cleaning towel.

This application is a continuation of conending application Ser. No.404,050, filed Oct. 15, 1964, which is now abandoned.

This invention relates to cleaning towels and, more particularly, tonovel and improved cleaning towels particularly adapted for cleaningglass or similar surfaces by first moistening the glass with water andthen Wiping the wetted surface with the cleaning towel.

Cleaning glass surfaces, such as windows and mirrors, as well as othersurfaces, has always been a distasteful and difiicult task. In recentyears a number of products have been developed for reducing the time andeffort involved and for providing improved cleaning. Among them arespecifically formulated liquid or semi-liquid cleaners which are sprayedor wiped on the glass surface and then removed with a cloth or papertowel. These products have the disadvantage of being susceptible ofspilling and leaving stains on carpets or furniture. In addition, sometypes of liquid cleaners must be allowed to dry on the glass surfacebefore being wiped away, thus slowing down the cleaning jobconsiderably.

Another suggested form of glass cleaning device is a paper substratecoated with a dry or wet cleaning composition. Such cleaning papers havethe advantage of being more convenient to use, inasmuch as they are usedalone or require only water to wet the surface before use.

All of the various known glass cleaners have one or more properties orcharacteristics rendering them somewhat ineifective or inconvenient. Forexample, some of the liquid products are first dried on the surface andthen wiped off. The cleaner comes oif as a dust, some of whichinevitably falls onto the Window sill, floor or furniture, for example,thereby necessitating separate cleaning up of the dust from the environsof the glass cleaning operation. This is also the case with previouslysuggested forms of dry-coated cleaning papers, which leave dust on theglass surface, on objects in the area of the cleaning and on the usersperson and clothes.

Another difliculty with some types of known glass cleaners is that theyleave streaks or lint on the glass surface, thereby necessitating extrawiping, such as with a moistened, lint-free cloth or a chamois to do athorough job. Additionally, some of the cleaners leave an oily filmwhich tends to collect dust. Others leave a water-resistant film whichmakes it difiicult to remoisten the glass when it is cleaned again, orin the case of car Windshields, forms vision distorting beads of water,even when the wipers are operated.

These and other disadvantages of present forms of glass cleaners areovercome, in accordance with the invention, by providing a novel andimproved cleaning towel comprising an absorbent web, such as a suitablepaper or cloth of natural or synthetic material, coated with a cleaningcomposition including porous, low bulk density cleaning powders, whichprovide optimum cleaning characteristics, and high bulk density carrierpowders, which have good coating properties and facilitate applicationof the cleaning composition to the web. The powders are adhered to thewebs by a binder in an amount sufficient to furnish a good bond withoutexcessively reducing the absorbency of the web or inhibiting thecleaning properties of the powders. The cleaning towel may also includea surfactant to complement the abrading action of the powders incleaning the surface.

The cleaning composition is preferably coated onto the web in the formof an aqueous slurry. Substances which may be included in the slurry tofacilitate forming a uniform coating having the desired coatingproperties are, for example, a dispersant to deflocculate the cleaningand carrier powders, and a thickener. It is also desirable from acommercial standpoint to include a colorant and an odorant in thecoating composition.

The cleaning towel, in accordance with the invention, has, among itsadvantages, a highly effective cleaning action and a relativelyinsignificant tendency to dust or lint. It is in completely dried formand requires only plain water, which is applied to the glass, for itsuse. Accordin gly, there is no danger of staining carpets and upholsteryas when the liquid type cleaners are spilled. Further, the coating paperleaves no oily, dust-catching film, depositing instead a beneficialwater-wettable film, which facilitates wetting the glass the next timeit is cleaned. The cleaning towels can be made at low cost, sold at avery modest price and are, of course, disposable.

In use, the user simply wets the glass or other surface with water andthen wipes the water and soil from the glass with the cleaning towel.The principal cleaning of the glass is accomplished by the abrasiveaction of the powders rather than by a chemical action. The dirt whichis abraded from the surface is absorbed together with the water into theabsorbent paper, the surfactant aiding the removal of dirt particles andoil film and absorption into and adsorption onto the towel.

In conjunction with the following detailed description of exemplaryembodiments of the cleaning towel, reference may be made to the figuresof the accompanying drawing, in which:

FIGURE 1 is a view in cross-section on a greatly enlarged scale of asmall piece of cleaning towel; and

FIG. 2 is a schematic diagram of a method of making the cleaning towel.

Referring to FIG. 1, the cleaning towel comprises a highly absorbent web10, preferably paper or other low cost material, having abrasiveparticles 12 adhered to it by a binder. Microscopic examinationindicates that the particles of powder are adhered to the surface fibersof the paper, there being just enough binder to make the powder stick.There is no discrete layer of binder, and

under the microscope, the surface of the paper is quite rough,consisting of holes and loosely interlocked fibers.

surfaces, thereby being placed in direct contact with the surfaces to becleaned when the paper is used.

The desirable properties of a cleaning towel, in accordance with theinvention, are obtained by a careful selection of both the absorbent weband the constituents of the coating composition. Additionally, theprocess of making the cleaning towels should be carefully controlled, inorder to obtain an optimum finished product.

As previously stated, the cleaning ability of the cleaning towelsappears to be principally a result of the physical properties ratherthan the chemical composition of the cleaning composition. Accordingly,the size, hardness, density and geometric form of the abrasive particlesare important. First of all, it has been determined that, preferably, atleast 40% by weight of the particles should be in the to 40' micron sizerange, inasmuch as particles smaller than 10 microns do not provide verysignificant abrasive action. Particles greater than 40 microns mayscratch the glass surface being cleaned, although particles havingsmooth rounded edges, such as those ground in a ball mill or those ofcertain materials, may be somewhat larger without harming the glass.Further, particles of relatively low hardness, say less than 3 Mohhardness generally are too soft to effectively abrade dirt from thesurface of the glass. Particles harder than glass can scratch glass andthus are to be avoided, unless they are free of sharp edges. Theparticulate materials used for the cleaning towels are, of course, waterinsoluble.

It has been found that particulate materials having the abovecharacteristics are usually of low bulk density and high porosity. Thepreferred low bulk density materials are suitably prepared diatomaceousearths and the pumices, the diatomaceous earths being sintered at hightem-v peratures to increase their hardness, and both, of course, beingground to the proper particle size range, as described above. Sand,insoluble phosphates and carbonates, ground glass, garnet, emery,silicon dioxide and tripoli powders have also been found to be suitableas cleaning powders. It is believed that such low bulk density powdersact as cleaners by (1) abrading the soil from the glass and (2)absorbing the loosened soil onto their surfaces which are of relativelylarge area. However, low bulk density powders generally possess poorcoating properties, that is, they tend to dry up a coating slurryprematurely, thereby causing a build-up of powder on the surface of thepaper which subsequently results in dusting.

Accordingly, the low bulk density cleaning powders constitute only aportion of the abrasive particles in the cleaning paper. The balance ofthe abrasive particles in the coating composition are relatively highbulk density materials which possess good coating properties, forexample, feldspars or feldspathoids, inasmuch as they are relativelynon-porous and non-absorbent and therefore do not dry out the coatingslurry. While the high bulk density powders, of course, provide a degreeof cleaning action, they serve generally as carriers for the low bulkdensity powders. Accordingly, they may best be termed carrier powders,whereas the porous, low bulk density particles may be termed cleaningpowders. Generally, the proportions of the cleaning powders to thecarrier powders should be between 1 to 6 and 1 to 1 by weight. A greaterproportion of cleaning powders tends to adversely affect the coatingproperties, whereas a lower proportion tends to excessively reduce thecleaning power of the cleaning towels.

Of equal importance in the cleaning towels is the web to which thecleaning composition is adhered. Because the cleaning action is, it isthought, principally a result of physical rather than chemical action,and more particularly, a result of abrasion, absorption and adsorption,the web should have high absorbency and a relatively smooth surface.Embossed or highly creped paper gives generally unsatisfactory results,since only a relatively small part of the surface area of the paper andcoating actually contacts the surface being cleaned.- However, a

4 number of desirable properties for the cleaning paper are present inslightly creped or semi-creped paper. Satisfactory grades are bleached,semi-creped, medium wetstrength, lint-free stock in the 25 to 60 poundbasis weight range.

Set forth in the table below are the specifications of a paper found toprovide excellent results in the cleaning towel. Particularly noteworthyare the high absorption properties and wet strength of this paper stock.

TABLE Basis weight, lbs., 24 x 36/500 33.25 Mullen, pts. 7.2 Caliper, in0.009 Absorption,-secs. 0.1 cc. water 3 Total absorption, water, percent193.5 Tensile, dry, oz.machine direction 75.5 Tensile, wet, oz.machinedirection 32.5 Stretch, percent 9.4

A number of binders to adhere the abrasive particles to the papersubstrate have been found to be suitable. Among them are proteins,starches, natural and synthetic gums, cellulose, rubber latexes, vinylacetate latexes and acrylic polymer latexes. Inasmuch as the coating isapplied to the paper in the form of a slurry, water soluble or waterdispersible binders are preferred, in view of their relative ease ofprocessing and handling, but they should have a low tendency toredissolve, which can often be provided by cross-linking ordenaturation. The binder in the composition is present in a minimalamount sufiicient to provide good binding, to sinter the particlestogether, and thus to provide a minimum of dusting of the powders andyet to prevent excessively reducing the absorbency of the cleaningpaper. Only a small fraction of the surface areas of the particles inthe composition are coated with the binder. It should be noted that thepresence of the carrier powders enables a significant reduction in theamount of binder necessary to obtain good adherence of the abrasivematerials over the amount that would be required if only the cleaningpowders were used. Therefore, the absorbency of the finished paper issubstantially higher.

Soft acrylic copolymer latexes, particularly Rhoplex B-5 (Rohm andHaas), a copolymer of ethyl acrylate and methylmethacrylate with a smallpercentage of either methacrylic acid or acrylic acid to supply pendantcarboxyl groups, provide excellent binding power and do notsignificantly effect the flexibility and handle of the paper orexcessively reduce its absorbency. Additionally, these binders have alow rewetting tendency, thereby limiting the extent to which the binderredissolves and reforms a slurry with the powders when the cleaningtowels are used. Therefore, the abrasive particles remain bound to theweb for a longer period during use and provide improved abrasive action.The optimum content of Rhoplex B-5 (46% solids content) in the coatingslurry is from about 2.6% to about 3.0% by weight of the slurry.

The addition of a plasticizer to polymeric binders may improve theapplication versatility of the slurry formula by aiding in the wettingof the powders and the fibers of the paper by the binder. For example,about 3% tributoxyethyl phosphate added to the acrylic latex improvesthe bond, and the finished cleaning paper has a lower tendency to dustand a faster absorbency time.

The amount of abrasive material in the cleaning towels is, of course, asignificant factor in determining their properties and characteristics.An unduly larger amount of powder requires a larger amount of binder,and the powder and binder together may reduce the cleaning power bylowering the absorbency of the Web. Further, excessive powder may causedusting. On the other hand, too little powder provides poor cleaning. Ithas been found that the best results are obtained with a coating ofabout 10% to 35% by weight.

As described hereinafter, the preferred method of making the cleaningtowels is by forming a slurry of the coating composition which is thencoated onto the substrate by roller coating or by immersion of the webin the slurry. In order to obtain a proper level of coating, that is,the proper pick-upof solids in the slurry onto the finished towels, itis necessary to control the rheological behavior of the slurry.Therefore, a thickener is preferably added to improve the flowproperties so that a uniform coating and impregnation of the papersubstrate is obtained. Additionally, thickeners inhibit the settling ofthe suspended powders in the slurry. A number of thickeners, some ofwhich also may serve 'as binders, are suitable, for example, natural orvsynthetic gums and cellulosic materials. Hydroxyethylcellulose hasseveral desirable properties as a thickener for the coating slurry, suchas not requiring special handling techniques, and its ability to bedispersed in water by normal agitation at room temperature. It can bemixed in powdered form with the abrasive powders. p

Another slurry additive which enhances even coating of the cleaningcomposition onto the paper substrate is a dispersant to assist theretaining of the .solids in suspension and also to defiocculate thecleaning and carrier powders. For example, atrace of tetrasodium. pyrophosphate provides improved coating properties in the slurry.

It is also desirable to include a surfactant in the cleaning compositioncoated onto the paper. A small amount of a surfactant causes atransitory foam to develop. on the wetted glass surface which aids inthe absorption. of water and soil onto the cleaning paper. It alsoappears that some surfactants, particularly sodium lauryl sulfate, leavea film on the glass surface which inhibits the spreading of oily soil,an important type of glass-soiling substance carried in the air, on theglass. Further, sodium lauryl sulfate renders the glass more wettable bywater; that is, water tends to spread more readily on glass having anadsorbed film of sodium lauryl sulfate. The optimum level of surfactantin the cleaningcomposition on the cleaning paper is an amount whichprovides a relatively slight transitory foam on the wetted glass. At lowlevels there is little effect on absorbency of the cleaning paper,-while at high levels the foaming action may be excessive, therebyinhibiting the pick-up of the water and soil from the glass, making itdifficult to remove the foam itself, and tending to leave streaks. I

The commercial attractiveness of the cleaning paper may be enhanced bythe addition of a suitable colorant and odorant to the coating slurry. 1

As previously stated, the preferred method of making the cleaning paperis to form an aqueous slurry of the cleaning composition and coat itonto the paper substrate. Referring to FIG. 2 of the drawings, the paperstock in roll form is fed from a supply roll 20* through a coating bath22 containing the slurry. The excess slurry is then removed from thepaper web by squeeze rolls 24. The coated paper is then dried, such asby passing it around a series of heated rolls 26. It is desirable toremove marginally bound and unbound abrasive powders from the paper,such as by brushing it with soft brushes or by passing it through a pairof soft polymeric foam sponges 28. With some types of stiff papers,brushing tendsto improve the drape and handle of the cleaning paper aswell as remove the loosely bound powder. The cleaning paper can then becut into convenient sized sheets or perforated at intervals so thatsheets can be torn from a roll by the user.

In the method there are several variables which are adjusted to providethe desired pick-up of cleaning composition onto the paper substrate.The important ones are the composition and coating properties of theslurry and the pressure of the squeeze rolls. Those skilled in thecoating art can readily provide the optimum conditions in the method toobtain the desired pick-up.

In use, the glass or other surface to be cleaned is first moistened byspraying or wiping water onto it, and the wetted surface is then rubbedwith a cleaning paper, which simultaneously abrades the soil from thesurface and absorbs the soil and the water. When one side of the sheetbecomes soiled, the sheet may be turned over and the other side used,and when it becomes saturated or completely soiled, it may thrown away.

Representative compositions for the cleaning paper, and an exemplarymethod of making the paper, in accordance with the invention, are setforth below.

The water was placed in a mixing vessel and the tetrasodiumpyrophosphate added under vigorous agitation. The thickener, cleaningpowder and carrier powder were then added rapidly to the liquid, alsowith agitation. When a homogeneous dispersion was obtained, theagitation was reduced and the surfactant solution and other ingerdientsadded in the order set forth.

A continuous roll of the paper substrate was passed through a bath ofthe slurry and the excess slurry squeezed from theweb by passing itbetween rollers. After the coated paper was dried, the surfaces werebrushed with a soft sponge to remove the marginally adhered powders. Thecleaning paper was then cut into sheets.

EXAMPLE II A coating composition was prepared according to the formulaset forth in Example I except that a polyvinyl chloride latexplasticized with dibutyl phthalate was substituted, at the sameconcentration, for the plasticized Rhoplex B-5 binder. The compositionwas applied to a paper substrate in the same manner as in Example I andproduced a comparable product.

EXAMPLE HI Ingredients: Parts by weight Water, tap 60.18 Carbopol 934 1%solution 15.00 Obsidian pumice (Celite Z-6) (cleaning powder) 8.00Nepheline syenite, peak grade (carrier powder) 8.00 Sodium laurylsulfate, 10% solution (surfactant) 2.00 Rhoplex B-S (binder) 2.80Colorant 10% solution 4.00 Odorant 0.02

Total 100.00

EXAMPLE IV Ingredients: Parts by Weight Water, tap 83.03 Tetrasodiumpyrophosphate (dispersant) 0.03 Hydroxyethylcellulose (thickener) 0.32Flux calcined diatomite (Hyfio Super Cel) (cleaning powder) 1.20Feldspar (Clinchfield 202) (carrier powder) 7.20 Sodium lauryl sulfate,10% solution (surfactant 3.00 Rhoplex B-5, 3% plasticizer (binder) 2.00

7 Ingredients: Parts by weight Colorant, l% solution 3.20 Odorant 0.02

Total 100.00

The coating compositions of both Examples III and IV were prepared andapplied to paper webs in the same way as those of Examples I and II.

Samples of the cleaning papers were distributed to a group of housewiveswho used them for cleaning windows and mirrors. They were found by mostusers to be convenient and easy to use, to leave no lint or dust, to beeffective cleaners, and to leave no streaks or film. Laboratory testsconfirmed these results.

Many modifications and variations of the invention as specificallydescribed herein will occur to those skilled in the art. Suchmodifications and variations are intended to be within the scope of theinvention as defined by the appended claims.

I claim:

1. A cleaning towel comprising a highly absorbent web coated with a drycleaning composition including a binder, a relatively'porous andabsorbent low bulk density cleaning powder and a relatively non-porousand non-absorbent high bulk density carrier powder, the carrier powderbeing present in an amount suflicient to inhibit the tendency of thecleaning powder to dry out a coating slurry of the cleaning powder andcarrier powder in a liquid vehicle and substantially all of the powdershaving particle sizes less than about 40 microns and at least 40% byweight having particle sizes greater than about microns.

2. A cleaning towel as claimed in claim 1, wherein there are from about1 part to about 6 parts by weight carrier powder to 1 part by weightcleaning powder.

3. A cleaning towel as claimed in claim 1 wherein the carrier powder isa member selected from the group consisting of feldspathoids andfeldspars.

4. A cleaning towel as claimed in claim 1 wherein the cleaning powder isa member selected from the group consisting of diatc-maceous earths andpumices.

5. A cleaning towel comprising (a) a highly absorbent web and (b) acleaning composition coated onto the web, the

cleaning composition including (i) a cleaning powder selected from thegroup consisting of diatomaceous earths and pumices, (ii) a carrierpowder selected from th group consisting of feldspathoids and feldspars,the

ratio by weight of carrier powder 'to cleaning powder being in the rangeof from about 1:1 to about 6: 1, (iii) a dispersant in an amountsufficient to deflocculate the powders,

(iv) a binder in an amount sufiicient to sinter the powders to the webwithout excessively reducing the absorbency thereof, and

(v) a surfactant in an amount sufiicient to provide a slight transientfoaming of the dried cleaning composition when it is rewet in use.

6. A cleaning paper comprising (a) a highly absorbent paper substrateand (b) about 10% to about 35% by weight cleaning composition coatedonto the substrate, the cleaning composition including (i) an obsidianpumice cleaning powder,

(ii) a feldspathoid carried powder, the ratio by weight of carrierpowder to cleaning powder being in the range of from about 1:1 to about6:1,

(iii) a dispersant in an amount sufficient to deflocculate the powders,

(iv) a plasticized acrylic polymer latex binder in an amount sufiicientto sinter the cleaning and carrier powders to the paper substratewithout excessively reducing the absorbency of the substrate.

(v) a small amount of thickener, and

(vi)- a small amount of sodium lauryl sulfate to provide slighttransient foaming of the cleaning position when it is rewet in use.

7. A cleaning paper as claimed in claim 6, wherein the carrier powder isnepheline syenite.

8. A cleaning composition for coating onto a web of absorbent material,comprising a relatively porous and absorbent low bulk density cleaningpowder and a relatively non-porous and non-absorbent high bulk densitycarrier powder, the carrier powder being present in an amount sufficientto inhibit the tendency of the cleaning powder to dry out coating slurrywhich includes the cleaning powderand carrier powder in a liquid vehicleand in particular the ratio by weight of the carrier powder to thecleaning powder being in the range of from about 1:1 to about 6:1, and abinder in an amount of sulficient to sinter the powder to the web ofmaterial without excessively reducing the absorbency of the web ofabsorbent material.

9. A cleaning composition for coating a paper substrate, comprising (i)a cleaning powder selected from the group consisting of diatomaceousearths and pumices,

(ii) a carrier powder selected from the group consisting offeldspathoids and feldspars, the ratio by weight of carrier powder tocleaning powder being in the range of from about 1:1 to about 6:1,

(iii) a dispersant in an amount sufiicient to deflocculate the powders,

(iv) a binder in an amount suflicient to adhere the powders to the papersubstrate without excessively reducing the absorbency thereof, and

(v) a surfactant in an amount sufficient to provide a slight transientfoaming of the dried cleaning composition when it is rewet in use.

References Cited UNITED STATES PATENTS 1,868,862 7/ 1932 Washburn 252-911,969,900 8/1934 Pickett 25291 2,395,054 2/1946 Levine 5 l400 2,627,1452/ 1953* Frigstad -1 5 l396 2,665,528 1/ 1954 Sternfield 5 l-4023,121,249 2/ 1964 Afileck 15506 3,121,249 2/1964 Aflleck l5506 OTHELL M.SIMPSON, Primary Examiner US. Cl. X.R. 51-295 PC4050 UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 1 7 95 Dated January27, 1970 Inventorcsk L. M. Prince It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

1-- Column 5, line 54 "drawings" should be I drawing Column 8, line 2"carried" should be carrier Column 8, line 16, "position" should becomposition Column 8, line 29 delete "of" before the word "sufficient";

Column 8, line 59 (references), "2,980,9 4/1961 Miller l5-506" should beinserted befo: "3,121 ,249 2/1964 Affleck -l5506";

Column 8, line 60 (references) "3,121,249 2/1964 Affleck '----l5506" isrepeated and shot be deleted.

SIGNED AND SEALED JUL? 1970 (SEAL) Attest:

Edward M. Fletch, 1:. WILLIAM E mm .1

O m Attestmg Officcr Commissions-r of Patents

